Colloid mill

ABSTRACT

A colloid or stirring mill in which the material to be treated mixed with millbodies, e.g. glass, ceramical or synthetic pearls, is moved in a container by means of one or more rotating milling members, the treated material being discharged through a sieve or filter eliminating the millbodies or pearls, the filter being rotated for avoiding choking of the filter.

June 4, 1974 United States Patent 1191 Funk 934 Crawford.

mm mmm n 0" Hi eye n mfikmn u r C me ndilov y a CWWWSLN 4 476 2 3355677 9999999 309422 6 [30] Foreign Application Priority Data Primary Examiner Donald 6 Kelly Assistant Examiner-Howard N. G

July 26. l97l Switzerland.1....,..... lO942/7l oldberg May 26, I972 Switzerland.............. 7796/72 Attorney Agent, or Firm-Imirie and Smiley 2 3 H H/ 1 4 2 1. M? M/ 4 1 9 4 2 m4 "2 C M U n 5 BOZc 17/16 241/4615, 69,

Field of Search synthetic pearls, is moved in a container by means of 181, 88, DK}, 7, 95, 65 one or more rotating milling members, the treated mater'ial being discharged through a sieve or filter elimi- References Cit d nating the millbodies or pearls, the filter being rotated UNITED STATES PATENTS for avoiding choking 0f the filter.

1.946.511 2/1934 Van 1. 24l/79 14 Claims, 5 Drawing Figures COLLOID MILL BACKGROUND OF THE INVENTION The invention concerns a colloid mill in which the material to be treated mixed with millbodies, e.g., glass, ceramical or synthetic pearls, is moved in a container by means of one or more rotating milling members, the treated material being discharged through a sieve or filter eliminating the millbodies or pearls.

In prior colloid mills of this type the separation of the treated material from the millbodies or pearls causes some problems. Sieves or filters rigidly fixed in the container run the danger of getting choked. So-called friction gaps through which the treated material escapes between a rotatable and stationary member have, above all, the disadvantage, that millbodies or pearls or fragments thereof are wedged in the gap and, therefore, may damage the gap walls and locally enlarge the gap width; splinters of the bodies or fragments may escape with the treated material.

SUMMARY OF THE INVENTION It is an aim of this invention to avoid these inconveniences by the fact that the sieve or filter rotates, the sieve or filter openings being provided on the circumference of a separator device. All the above mentioned disadvantages of prior mills can be avoided in this way. Experience has proved that, under certain conditions, wear and tear of of the sieve or filter can be held to within negligible limits, although friction between the outer filter surface and the millbodies or pearls cannot be entirely prevented.

The accompanying drawings illustrate, by way of examples, three embodiments of separator devices of the colloid mill according to the invention, additional parts of the colloid mill being shown for the third example.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a part of the separator device of the first example.

FIG. 2 is a sectional view of a part of the separator device of the second example.

FIG. 3 is a side view of the filtering disc of the second example.

FIG. 4 is a sectional view through a portion of the mill of the third example and FIG. 5 is a section along line V V of FIG. 4.

DESCRIPTION OF THE INVENTION In FIG. 1 the outer portions of two discs 1 and 2 belonging to the separator device of a rotatable stirring or colloid mill are shown. They'are rigidly mounted on a rotatable shaft not shown in FIG. 1, such as, for instance, on a shaft 14 according to FIG. 3 or FIG. 4. Also rigidly mounted on this shaft are one or more discshaped milling members such as, for instance, discs 18 as shown in FIG. 4.

Between the two separator discs 1 and 2 in FIG. 1 there is a cylindrical hollow space receiving the treated material, this space being connected with an outlet for the treated material, for instance, through bores 15 of the hollow shaft 14 according to FIG. 3. The discs 1 and 2 of FIG. 1 have each an inner shoulder la and 2a respectively. These shoulders 10 and 2a are engaged by a cylindrical sheet metal supporting or reinforcing ring 3 having slits or oblong holes 4. On the ring 3 bears a cylindrical ring 5 of a particularly abrasionproof plastic or other synthetic material. This ring 5, constituting a sieve or filter has slot holes 6 widening from the exterior towards the interior, ie in the flow direction of the treated material flowing into the hollow space between the discs 1 and 2. The clear width of the slot holes 6 is dimensioned in such a way that the millbodies consisting, for instance, of pearls made of glass, ceramics or plastic material, cannot pass through these holes 6. Should in spite of that, foreign bodies enter into a hole 6, they can, due to the widening of the slots towards the inside, pass through it so that a choking of the sieve or filter 5 is avoided. Thorough tests have proved that the plastic ring 5 reaches a very high servicetime. At the same time, the millbodies or millpearls are precluded from damage in that, on possible impact onto the relatively rapidly rotating plastic ring 5, they are not under heavy stress or strain. Although the illustrated slot holes 6 and 4 respectively proove very good, any other perforation of the plastic ring 5 and/or the supporting ring 3 may be provided. If the surfaces of the supporting ring 3 and the plastic ring 5, contacting each other, have a suitable structure so that between the members 3 and 5 there exists a system of many transverse channels, the holes 4 of the supporting ring 3 need not coincide with the holes 6 of the plastic ring 5. If the axial width of the sieve or filter 5 between the discs 1 and 2 is small and/or the thickness of the plastic ring 5 is chosen large enough and/or the working pressure is low enough, the supporting ring 3 can, if desired, be omitted.

In the example illustrated in FIGS. 2 and 3, the filter is constituted by a pile ofrings or discs 7 lying between the two discs 1 and 2 of the separator device. As is shown in FIG. 3, the discs 7, taken along by the discs 1 and2, are secured in their position relatively to one another by pins 8 axially traversing them. Each of the discs 7 has an axial annular flange 9 from which ribs 10 of the same axial height extend radially inwards and between them radial passage channels 11 are formed. The distance between adjacent discs 7 and thereby the clear width of the filter slots 12 is determined by spacer rings 13 inserted between the discs 7. The desired clear width of the filter slots 12 can be determined by a suitable choice of the thickness of the spacer rings. As illustrated in FIG. 3, the discs 1 and 2 are fixed on a hollow shaft 14, into which the treated material can escape from the collecting space between the discs 1 and 2 through bores 15 of the shaft 14 flowing through this shaft to an outlet not shown.

The working manner of the embodiment according to FIGS. 2 and 3 is easily to be understood. The treated or milled material flows through the filter slots 12, from here through the channels 11 into the collecting space between the discs 1 and 2 and from there on the just described path through the hollow shaft 14 out of the colloid mill. The discs 7 may consist of any suitable material, preferably also of an abrasion proof, artificial or synthetic material. Also the discs 1 and 2 may in both embodiments according to FIGS. 1 to 3 consist of abrasion proof material such as plastic or other synthetic material or their outer surfaces may be coated with such an abrasion proof material.

In spite of the advantages offered by the colloid mills according to FIGS. 1 to 3, choking may occur when treating certain kinds of material, for instance, on treating thixotropic liquids such as, thixotropic colors or dyestuffs, whose tendency to form a gel can choke the sieve or filter openings by forming lumps.

With the aid of the third example according to FIGS. 4 and 5 even such choking, such as, for instance, the gel formation of thixotropic liquid before the outlet from the colloid mill, can be avoided. As is well known, thixotropy is the property possessed by certain gels of liquifying under the action of beating or vibrating forces.

In the embodiment of FIGS. 4 and 5 this is achieved by the fact that inside the rotating sieve or filter of the separator device, eliminating the millbodies or millpearls, a stripper is provided. This stripper does not only prevent choking when treating thixotropic liquids but also on treating other material liable to choking for other reasons.

Within a conical vessel 16 of the colloid mill according to FIGS. 4 and 5 with a cooling jacket 17, milling members in the shape of discs 18 placed at a distance from each other are rigidly arranged on the rotatable shaft 14, as is the case, though not shown, in the two first examples. The material to be treated is mixed with millbodies 18a, such as, e.g., glass, ceramical or plastic or other synthetical pearls, and is moved in the vessel 16 from right to left in FIG. 4. After eliminiation of the millbodies or pearls at the separator device, the treated material finally leaves the mill through the outlet 19. By the side of the outermost milling disc 18 (left in FIG. 4) the separator device with its sieve or filter openings 6 is provided. This device has a flange 22.0f a tub'epiece 23, this flange being rigidly connected by means of bolts 21 traversing sleeves 20, with the left-hand disc 18 rotating with the shaft 14. The tube piece 23 is tightened against the stationary wall 25 of the vessel 16 by means of a slide ring seal 24. The annular sieve or filter 26 comprising the openings 6 is rigidly connected with the outermost lefthand disc 18 (FIG. 4) and with the flange 22, so it rotates with the shaft 14 as in the two first examples. Inside the annular sieve or filter 26 there is a wheel 27 with strippers 28. This wheel 27 is rigidly connected with the wall 25 by means of a tube 33, so that it cannot rotate. The tube 33 is provided with passage holes 29 through which the treated material freed from the millbodies or pearls can reach the annular space 30 and from here flow through the passages 31, 32 in the discharge conduit 19.

As illustrated in FIG. 5 the strippers 28, in rotating direction D of the sieve or filter 26, are inclined forwardly from their outer end towards their inner end. The strippers 28 extend from the internal surface of the sieve or filter 26 up to the exit, i.e., up to the stationary tube 33. At least at their ends adjacent the sieve or filter 26 the strippers 28 have the shape of knives.

In another embodiment of the invention there may also be provided only one or two or more than three strippers.

Under certain condition it may be suitable to provide in another embodiment rotatable strippers 28 which, of course, rotate at a speed different in value and/or direction from that of the filter 26.

If, on treating thixotropic material, there is, on the passage through the filter openings in the direction of the arrow A, the tendency of gel formation and thereby the danger of choking, this choking is prevented by the stirring and scraping effect of the strippers 28. In other words, the passage of openings 6 across the edges of strippers 28 as the shaft 14 rotates, causes an intermittent interruption in the unhindered flow of material through the filter such that the material experiences certain vibration forces which prevent gel formation. The effect along with the scraping action is similar with treated material apt to form lumps for reasons other than the tendency to form a gel.

I claim:

1. A stirring mill comprising, a container to receive a mixture of material to be treated and of millbodies, an outlet from said container for the treated material, a rotatable shaft traversing said container, a plurality of milling members rigidly connected with said shaft and spaced from one another, and a separator device in rigid connection with said shaft immediately adjacent a side wall of one of said milling members and forming a hollow space communicating with said outlet, said separator device comprising a circumferential filter rotating with said shaft and having openings widening in the direction of flow of the treated material for retaining said millbodies from said hollow space.

2. A stirring mill as claimed in claim 1, said filter consisting of synthetic material.

3. A stirring mill as claimed in claim 1, said filter having elongated gap openings lying in circumferential direction.

4. A stirring mill as claimed in claim 2, wherein said separator device includes a circumferential perforated supporting ring, said synthetic filter being supported on said supporting ring.

5. A stirring mill as claimed in claim 1, said filter comprising a plurality of piled discs, forming'slots between them.

6. A stirring mill as claimed in claim 5, said piled discs having on their circumference axially projecting annular flanges, and further having radial ribs forming passage channels between said ribs, said separator device including spacer rings between said piled discs to determine the clear width of the slots between the piled discs.

7. A stirring mill as claimed in claim 5, said piled discs consisting of synthetic material.

8. A stirring mill as claimed in claim 1, including at least one stripper inside the rotating filter disposed adjacent said openings in said filter to preclude blockage of said filter by material passing therethrough.

9. 'A stirring mill as claimed in claim 8, said stripper being stationary.

10. A stirring mill as claimed in claim 8, wherein several strippers are arranged about a stationary wheel.

11. A stirring mill as claimed in claim 8, wherein said stripper is inclined with respect to the circumferential surface of said filter.

12. A stirring mill as claimed in claim 8, whereinsaid stripper extends from the internal surface of said filter to the exit of said separator device.

13. A stirring mill as claimed in claim 8, wherein said stripper, at least at its end adjacent said filter, has a knife edge.

14. A stirring mill as claimed in claim 1, wherein the separator device is fixed to said one adjacent milling member, said milling member forming a side wall of the separator device. 

1. A stirring mill comprising, a container to receive a mixture of material to be treated and of millbodies, an outlet from said container for the treated material, a rotatable shaft traversing said container, a plurality of milling members rigidly connected With said shaft and spaced from one another, and a separator device in rigid connection with said shaft immediately adjacent a side wall of one of said milling members and forming a hollow space communicating with said outlet, said separator device comprising a circumferential filter rotating with said shaft and having openings widening in the direction of flow of the treated material for retaining said millbodies from said hollow space.
 2. A stirring mill as claimed in claim 1, said filter consisting of synthetic material.
 3. A stirring mill as claimed in claim 1, said filter having elongated gap openings lying in circumferential direction.
 4. A stirring mill as claimed in claim 2, wherein said separator device includes a circumferential perforated supporting ring, said synthetic filter being supported on said supporting ring.
 5. A stirring mill as claimed in claim 1, said filter comprising a plurality of piled discs, forming slots between them.
 6. A stirring mill as claimed in claim 5, said piled discs having on their circumference axially projecting annular flanges, and further having radial ribs forming passage channels between said ribs, said separator device including spacer rings between said piled discs to determine the clear width of the slots between the piled discs.
 7. A stirring mill as claimed in claim 5, said piled discs consisting of synthetic material.
 8. A stirring mill as claimed in claim 1, including at least one stripper inside the rotating filter disposed adjacent said openings in said filter to preclude blockage of said filter by material passing therethrough.
 9. A stirring mill as claimed in claim 8, said stripper being stationary.
 10. A stirring mill as claimed in claim 8, wherein several strippers are arranged about a stationary wheel.
 11. A stirring mill as claimed in claim 8, wherein said stripper is inclined with respect to the circumferential surface of said filter.
 12. A stirring mill as claimed in claim 8, wherein said stripper extends from the internal surface of said filter to the exit of said separator device.
 13. A stirring mill as claimed in claim 8, wherein said stripper, at least at its end adjacent said filter, has a knife edge.
 14. A stirring mill as claimed in claim 1, wherein the separator device is fixed to said one adjacent milling member, said milling member forming a side wall of the separator device. 